During most field support operations, it is frequently necessary to disassemble ponderous, heavy equipment and transport it to a machine shop in order to refit joint and pivot elements of articulating parts with new bearing bores, bearings or bearing sleeves. It is only at large machine shops or refurbishing plants that the equipment necessary to reestablish bore alignment in such jointed or articulating machinery is found; most often a large, horizontal mill borer must be used. Such machinery is necessitated by the need to reestablish smooth bores or bushing surfaces that are aligned, axially and concentrically, so that new bearings or bearing sleeves may be refitted. In most instances, especially with the advent of high volume loader buckets, individual boring, reaming or rigorous honing cannot be accomplished effectively and efficiently and a ganged operation, such as the placement of multiple tools on a single coaxial alignment shaft, is employed. Another very severe drawback in the present art, as it relates to the aforementioned heavy equipment, is the inability of any apparatus known to the inventor that will effectively rebore a plurality of eccentrically worn bearing bores, in whatever orientation the loader arm or bucket arm has been grounded. In situations where the equipment is still removed to the refurbishing plant, this is of no consequence because, after going to the expense, time and energy to remove the work piece, proper orientation of it on a horizontal mill borer becomes but an adjunct function.
The instant inventor has long sought to overcome the necessity of removing heavy equipment to a machine shop or a refurbishment plant. Others, also, have sought to overcome the problem and to this end they, and the instant inventor, developed in-situ machines for refurbishing bores, especially bearing bores, in a workpiece. Precursors to the modern, in-situ boring machine comprised numerous portable boring machines that employed hand drills to rotate boring bars. The limitations inherent in such devices were, to those skilled in this art, intuitively obvious because such portable devices failed to provide the accuracy necessary to refurbish a plurality of worn, axially aligned bores. This problem stemmed primarily from the difficulty encountered in first achieving, and subsequently maintaining, alignment of the hand drill with the original common bore alignment axis.
To resurface and realign a plurality of worn bores that are disposed in-line, i.e. the true centers of the original holes were coaxially aligned, a machining system is required that may be easily mounted on or about the various types of equipment in-situ. A current state of the art machine claiming such facility was disclosed in U.S. Pat. No. 4,580,931, which issued to Wilger et al, on Apr. 8, 1986. Wilger describes and discloses what he terms an in-situ machine for refurbishing a bore in a workpiece. The invention includes a shaft which is adapted to be fixed to the workpiece in axial alignment therewith and a tubular boring element concentrically mounted for rotation about the shaft, adapted to extend into the workpiece bore. Mounted on the boring element for reciprocal movement therealong is a cutting head. By one device, the cutting means is rotated while another device, responsive to the rotator device, is employed to advance the cutter head along the tubular boring element. The Wilger device is mounted in-place to a pair of bearing bores; but the alignment, and even the apparatus disclosed, cannot be reasonably extrapolated for use with a multiplicity of bores that, although having originally been in coaxial alignment, have suffered such spalling, burnishing, erosion and even elliptical distortion of the workpiece surface to the extent that reasonable refurbishment could possibly require the establishment of a new common axis of alignment. Further, and what is most evident from the analysis of the Wilger invention, an attempt to translate a cutting tool over a very lengthy working axis, with the attachment only to surfaces of the workpiece, would induce deflection of either the tubular boring element or the fixed shaft's thrust bearing, resulting in an eccentric bore or possible nonconcentricity of one or more of the bores in a plurality. This problem stems primarily, in the general case, from the fact that most heavy equipment bearing holders or bushings are not perpendicular to the forks, tongues or flanges of the equipment joints. Oftentimes, the joint elements bearing the bores are cast and their external surfaces are not parallel or they are, at best, irregular. The problem also stems from the reason that very heavy loader arms may be grounded so that the outside of one of the bores is almost touching the ground. Thus, a portable borer (such as the invention of U.S. Pat. No. 4,589,931 cannot be clamped to the exterior surfaces of the equipment that is in close ground proximity.
Wilger could have overcome this latter deficiency, that of being unable to bore essentially downward (since the bore containing arm or flange is "grounded"), by providing a means for stabilizing his tubular boring element shaft with reference to the grounded arm/flange. The instant inventor has devised a boring shaft which can be journaled in a pillow block, a moveable pillow block, to overcome the Wilger device's most significant deficiency. The pillow block is mounted either on a second portable jig or, to provide an inside stabilization vis-a-vis the grounded arm/flange, is tack-welded to the arm/flange's inside surface, superposed on the outer bore.
The instant inventor has further determined that, in addition to a device that would resurface and realign a plurality of worn bores on various types of equipment in-situ, a cutting means must be provided that readily lends itself to the resurfacing of a variable number of worn bores without the necessity of successive and repetitive, as well as time consuming, alignments. Proper alignment, being of paramount consideration in a boring-reaming operation, a portable boring machine must inculcate means that would allow it to be omni-directionally aligned. An omni-directionally alignable base jig mechanizes such a means.